Method and apparatus for filling dental cavities



Jan. 14, 1969 Filed March 23. 1966 R. L. NEWMAN 3,421,222

METHOD AND APPARATUS FOR FILLING DENTAL CAVITIES Sheet of 2 Jan. 14, 1969 l R1., NEWMAN 3,421,222

METHOD AND APPARATUS FOR FILLING DENTAL CAVITIES United States Patent O 3,421,222 METHOD AND APPARATUS FOR FILLING DENTAL CAVITIES Roy L. Newman, 1023 Lundvall, Rockford, Ill. 61107 Filed Mar. 23, 1966, Ser. No. 538,459 U.S. Cl. 32-15 17 Claims Int. Cl. A61c 5/12; A61k 5/02 ABSTRACT OF THE DISCLOSURE The method includes securing a form over a cavity and providing an opening in the form, inserting a barrel through the opening and into the cavity, and introducing filling material through the barrel to iill the cavity from its inner portion toward the form. The disclosed apparatus includes a dispenser, several types of dental forms, a clamp, and a tool for providing the opening in the forms. The dispenser is operated by air pressure and has a removable cartridge in which the filling material may be prepared.

This invention relates to a method and apparatus for lling a cavity in a tooth.

It is an important object of this invention to provide a new and useful method and apparatus for filling cavities in teeth faster and easier than existing methods and apparatus.

Another object is to provide a method and apparatus for filling dental cavities in `both anterior and posterior teeth.

It is another object of the invention to provide a method and apparatus for iilling dental cavities and for procuring substantially perfect marginal adaption of the filling material on all portions of the cavity margins.

Still another object is to provide a method and apparatus in accordance with the above and which is usable for restoring incisal edges and crowns of teeth.

Another object of this invention is to provide a method and apparatus in accordance with the above object which provides substantial savings in cost.

Yet another object of this invention is to provide unique dental forms for use in the method of filling a cavity in a tooth.

Other objects and advantages of this invention will become apparent as the method and apparatus become better understood by reference to the following specification taken in conjunction with the accompanying drawings wherein:

FIGURE l is illustrative of the method of the present invention being used to ll a cavity in an anterior tooth and includes a view, in part perspective and in part diagrammatic, of a typical apparatus for performing the method;

FIG. 2 is illustrative of the method of the present invention being used to crown a posterior tooth;

FIG. 3 is a partial sectional view taken generally along lines 3-3 of FIG. 1;

FIG. 4 is an elevational view of a matrix strip constructed in accordance with the present invention;

FIG. 5 is a sectional view, on a larger scale and with exaggerated thickness, taken along lines 5 5 of FIG. 4;

FIG. 6 is an elevational view of another matrix strip constructed in accordance with the present invention;

FIG. 7 is a cross-sectional view taken along line 7--7 of FIG. 6 and on a larger scale and having exaggerated thickness;

FIGS. 8 and S-A are perspective view of embodiments of tooth forms constructed in accordance with the present invention;

Patented Jan. 14, 1969 FIG. 9 is a longitudinal sectional view of a dispenser for filling material constructed in accordance with the present invention;

FIG. l0 illustrates a tool for securing a barrel to the end of a dispenser;

FIG. 11 illustrates a tool for removing the barrel and cartridge from the end of the dispenser after use;

FIG. l2 is a large-scale top plan view of a matrix clamp constructed in accordance with the present invention;

FIG. 13 is a front view of the matrix clamp of FIG. 12;

FIG. 14 is an end view taken along line 14-14 of FIG. 13;

FIG. 15 is an elevational view of a dental tool constructed in accordance with the present invention for cutting an opening in a matrix strip; and

FIG. 16 is an end view taken along line 16-16 of FIG. 15 and on a much larger scale.

Reference is now made more particularly to the drawings wherein similar reference characters indicate similar parts throughout `several views. A plurality of anterior teeth 20-22 are illustrated in FIG. 1 and a plurality of posterior teeth 24-29 are illustrated in FIG. 2. The method of the present invention is particularly adapted for repairing or restoring damaged teeth. For example, the method may be used for iilling a cavity 21a as in tooth 21; it may be used for repairing the incisal edge of a tooth; or it may be utilized for crowning as on tooth 25, or other repairing applications. Such repairs, in general, may hereinafter be sometimes referred to as cavities and it should be understood that this term may include any condition of a tooth which requires repair. While the drawings indicate repairing a cavity in an anterior tooth and crowning a posterior tooth, this is for illustrative purposes only and it should be understood that the present invention is not so limited.

The cavity 21a or 25a may be prepared for filling in the usual manner as, for example, undercutting the sides in a generally key-shape (FIG. 3) or, when a larger portion of the tooth is missing, providing a shoulder preparation by making all margins square and solid thereby avoiding thin, tapering edges (FIG. 2). The cavity preparation may include lining the cavity with a cement, a primer, or a pulp-capping composition. The preparation may also include moisture exclusion by physical or chemical means to exclude moisture from the cavity during placement of the filling material.

Following the preparation of the cavity, a form is secured in position over the cavity. The type of form used depends on the character or type of cavity being filled. For example, if the cavity is in the side of the tooth, a matrix strip such as shown in FIGS. 4-7, may be used. If an incisal edge or occlusal surface is to be repaired, or the tooth crowned or capped, a tooth form such as shown in FIGS. 8 and 8-A, may be used. While such repairs may hereinafter sometimes be referred to as applying to an incisal edge it should be understood that this includes occlusal surfaces. Also, tooth forms and matrix strips may hereinafter be referred to as forms or dental forms and it should be understood that such terminology is not limited to a particular type of matrix, tooth form or the like.

The matrix of FIGS. 4 and 5, generally designated 32, is advantageously made of synthetic resin and has a height less than the overall height of an ordinary tooth and a length substantially greater than the circumference of the tooth. While the thickness may vary in accordance with the strength of the material, the emb'odment illustrated has a thickness in the range of about .002-.004 inch. Approximately mid-way between the ends of the 3 strip is provided a generally U-shaped slot 33, conveniently formed by a punching operation. The slot defines a ap 34 which is flexible and movable laterally from the strip about a line connecting the ends of the slot to provide an opening in the matrix strip, as shown in FIG. 5.

The matrix strip shown in FIGS. 6 and 7, generally designated 42, has a shape approximating that described above for matrix strip 32. Matrix strip 42 comprises a first elongate strip 44 having a plurality of openings 45 located in a central portion intermediate its ends. A second fiexible strip 46 is secured to the first strip in any convenient manner and underlies the openings to provide a closure therefore. The second strip is preferably made of synthetic resin which is readily rupturable for rupturing by a total inserted through a selected opening 45, but strong enough to span the adjacent openings 45 without dishing into the openings when the cavity is filled with material. Preferably the second strip is sufficiently resilient to substantially reclose the opening when the tool is removed therefrom. For small cavities, the first layer may be of synthetic resin about the thickness described above for strip 32. For larger cavities, the first layer is advantageously stainless steel to provide greater strength to Span the cavity. With the plurality of openings, preferably spaced in staggered relationship, as shown, the dentist is assured that at least one opening overlies the cavity. As an aid in visually locating the openings, the first layer is preferably colored yand the second layer is preferably transparent. I have found that a blue first layer is particularly advantageous and that the contrast between it and ya clear second layer makes it easy to locate the opening over the cavity. It is contemplated that matrix 42 may also be constructed of one layer having a plurality of openings 45 therein and that these openings be at least partially refilled with a readily ruptura-ble synthetic resin. It is necessary, however, that the underside of the matrix provide a smooth surface to overlie the cavity. As indicated above, it is preferably that the rupturable synthetic resin be resilient to substantially reclose when the tool is removed therefrom.

A tooth form 48 (FIG. S-A) is preferably utilized when it is necessary to repair the incisal edge of a tooth. To provide access for filling a cavity, an opening 49 is preferably provided in wall 50 of the tooth form. A tooth form or cap forms 52 (FIG. 8) is used when it is necessary to crown or cap a tooth. To provide access for the filling of the cavity, as shown in FIG. 2, an openings 54 is provided in wall 53 of the tooth form.

While either matrix strip 32 or 42 is advantageously utilized for filling cavity 21a, FIG. 1 illustrates matrix 32 in use. Prior to positioning, the strip may be pulled over the rim of a dentists mirror or any round edge to concave the surface and avoid cupping the filling. This is particularly applicable to large cavities. The opening in matrix 32 is positioned over the cavity 21a and the strip is doubled upon itself to provide a loop extending around the tooth 21 and with the end portions of the strip in juxtaposition. The dentist then pulls on the end portions to tighten the central portion of the strip against the tooth and clamps the end portions in an area adjacent the tooth to hold the central portion tightly against the tooth. The clamping is advantageously performed with a matrix clamp 61.

A preferred matrix clamp, generally designated 61, is illustrated in FIGS. l2-14. The clamp comprises elongate members 62, 63 having inwardly tapered portions 62a, 63a and opposed nose portions 62b, 63b. Each nose portion is provided with a plurality of five teeth 64 arranged to intert with teeth of the opposite nose portion. The outer surface of nose portions 6211, 6317, is preferably concave, as shown in FIG. 13, to generally conform to the labial surface of a typical anterior tooth. In this manner, when clamped on a matrix strip, the strip is gripped closely adjacent the tooth over its entire width.

Adjacent one side of the 'clamp are v`arms 65,' 66 mounted on members 62, 63, respectively. The arms are pivotally connected by means of a fastener 67 and arm 65 conveniently has a rearward extension for mounting a spring 68, as by fastener 69. The spring is advantageously U- shaped and has its legs extending sidewardly and upwardly into engagement with members 62, 63. It will be noted that this arrangement of arms 65, 66, and spring 68 is disposed generally at a side of the members `62, 63 thereby leaving the Iarea therebetween substantially open for reception of a matrix strip. After the matrix is looped around a tooth and its end portions placed in juxtaposition, the yclamp is easily opened and slipped over the matrix strip from the side opposite arms 65, 66. With this arrangement there is no interference with the matrix strip and the strip is held closely adjacent the labial surface of an anterior tooth across the entire width of the str1p.

When a tooth form, 48 or 52, is to be used, one 0f proper size is first selected. Preferably, the size of the form is such that it closely engages the surface of the tooth. The position of opening 49 or 54 is then selected and the opening formed by any convenient manner as -by a dental burr. The form is then slipped onto the tooth and properly positioned. When repairing an incisal surface, proper aligning and positioning is important, likewise, when capp-ing a tooth, a proper occlusion is important, and the dentist may have the patient bite, as shown in phantom in FIG. 2, to aid in positioning the tooth form. When such positioning is determined, the form is advantageously held by a layer of dental wax 57 which is applied to the surface of the tooth form and adjacent tooth surfaces. It can be seen'that this procedure is advantageous since the proper occlusion or alignment of the incisal edge is determined prior to filling the cavity or repairing the tooth. Wedges 56 are inserted between the tooth form and an adjacent tooth to keep the material from oozing into the gum area.

After the dental form is secured into position in a manner described above, the cavity is ready to be filled. A particularly advantageous dispenser for this purpose is described below.

A filling material dispenser, generally designated 70, is illustrated in FIG. 9. The dispenser has a generally cylindrical elongate body portion 72 having an internal compartment 74 adjacent its left end as viewed in FIG. 9. A removable cartridge is disposed in the compartment 74 for holding the filling material and includes a preferably tubular body portion 76 and having a piston disposed therein. The piston includes a tapered rubber plunger 78 and a plastic insert 79. The rubber plunger is movable toward the left end of the compartment to force the filling material out of the compartment and has annular flanges 78', 78" (FIG. ll) in engagement with the inner wall of body 76 to generally provide a seal therewith and force substantially all the material out the compartment. A closure assembly, generally designated 81, is arranged to overlie the end of the body 72 and has a cap 82 and a neck portion 83 for insertion between the body and the cartridge as shown in FIG. 9. Bayonet slots 84 are provided in the body 70 for receiving pins 85 to hold the closure at the end of the dispenser and to tighten the cartridge body 76 against the rear side of compartment 74. Closure 82 has an opening 86 therein, through which extends a cartridge closer. As shown, the cartridge closer includes a cover portion 91 fiaring outwardly from the cartridge atan angle generally complementary to the surface of the plunger 78. In this manner the plunger may force substantially all the material from the cartridge. A hollow neck portion 92 communicates with the cartridge and is generally coaxial with the cartridge inner surface. A neck engaging member 93 is frictionally secured to the neck portion 92 and has a barrel 94 extending therefrom. For use in the present invention, the outer diameter of barrel 94 is less than the size of the cavity and the inside diameter is of a size sufficient for passage of a flowable filling material therethrough. The extremity of barrel 94 may be generally square, as shown, or tapered slightly to provide a sharp cutting edge for easily piercing second layer 46 of the matrix strip (see FIG. 7).

Closure 82 has a generally U-shaped spring 87 thereon and adjacent one end of neck 83 for engaging and supporting cover portion 91 in position. For this purpose, a tool 102 is provided. The tool comprises a base portion 103 and a generally upright head 104 on the base. Head 104 has a diameter approximating that of cartridge body 76 for engaging cover portion 91. The neck and barrel assembly is loosely inserted through opening 86 and inverted on tool 102, as shown in FIG. 10. Cover portion 91 is engaged and held by spring 87 by movement of closure 82 in -a direction indicated by arrow 105 in FIG. 10.

FIG. 11 illustrates another tool, generally designated 106, for use in removal of the barrel and neck assembly after the dispenser has been used for filling a cavity. Second tool 106 includes a base 106 and a generally upright tubular body 108 attached thereto. Tubular body 108 has an inner diameter sucient for receiving neck engaging portion 93 therebetween and has a length suflicient s0 that its upper end may engage flange 93 of tube engaging portion 93. After use of the dispenser, the cartridge is advantageously removable from the cavity along with the closure assembly 81. Thus, for removal of the neck and barrel assembly and the cartridge from closure 82, neck engaging portion 93 and barrel 94 are inserted into tubular member 108 until flange 93 engages the end of tubular member 108. Further movement of closure 82 in a direction indicated by arrow 109 disengages the neck and barrel assembly and the cartridge from the closure. The cartridge and neck and barrel assembly are conveniently made of relatively inexpensive materials so that these portions may be discarded after use, thereby eliminating the necessity of cleaning any parts of the dispenser.

An exemplary means for dispensing materials through the barrel is illustrated in the right hand portion of FIG. 9 and is disposed in the hollow cylindrical portion of body 72. As illustrated, the body defines a second compartment 111 communicating with internal compartment 74 and a third compartment 113 communicating with second compartment 111 and having a larger diameter for reason which will hereinafter become apparent. A plunger assembly, generally designated 115, is disposed in compartments 111 and 113 and includes a ybody portion 117 and a head portion 116, of slightly larger size, attached thereto. A first sleeve 118 is disposed `around the left end of body 117 and a second sleeve 119 is attached to the right hand end thereof as by fastener 121. A compresslon type spring 122 is disposed around body 117 and extends between sleeves 118 and 119. The spring holds the plunger assembly in the position illustrated with the rear edge of head 116 engaged with sleeve ange 118'. The right hand end of dispenser body 72 is conveniently threaded for receiving a threaded closure 124 thereon. An insert 125, conveniently made of plastic, is held by the threaded closure and has a metal tube 126 extending therethrough. Tube 126 conveniently has a collar 127 disposed outside of insert 125 for reception of an air line coupling through which air may be fed under pressure to third compartment 113. Such a supply of gas under pressure is usual in dentist offices and includes la supply S and a valve V disposed in air line 128 (FIG. 1) which may be coupled to tube 126. When the valve V is opened, air, conveniently under 30 p.s.i. pressure, is fed through line 12S and tube 126 into third compartment 113. A gasket 131 is mounted on second sleeve 119 and is arranged to engage the surface of third compartment 113 whereby the air pressure Will cause the plunger to move into engagement with piston insert 79 vand dispense material through the barrel. At the extremity of the movement, sleeve 119 will engage sleeve 11S thereby controlling the movement of head 116 thereby preventing any excessive pressure against closure assembly 81. An air vent 133 is provided -in body 72 and communicating with second chamber 111 to relieve any compression during movement of the plunger for dispensing and to relieve the interior to atmosphere when air pressure is removed, thereby allowing the plunger assembly to return the position illustrated.

A suitable material for use in the method is Bonl sold by L. D. Caulk Co. of Milford, Del. This material, when mixed in accordance Iwith instructions is readily owable and lends itself for use in the present invention. The removable cartridge may advantageously be used as a receptacle 1for mixing the material preparatory to use. It can be seen that the cartridge can stand upright on its right end, as viewed in FIG. 9. Also, its opposite end is generally open to provide access for the insertion of materials to be mixed. The tight seal provided by flanges 78', 78" on plunger 78 prevent the loss of material during such mixing.

It is now deemed obvious that the above described apparatus can be utilized to quickly and easily fill dental cavities. In the method illustrated in FIG. 1, a matrix strip is secured in position. The tubular barrel 94, which has an outer dimension less than the size of the cavity, is inserted through an opening in the form and into the cavity. A llowable filling material, as at 135 in FIG. 3, is dispensed through the tubular barrel and into the cavity. Since the barrel is disposed inside the cavity, it can be readily seen that the first amount of material dispensed will be dispensed in the rear portion of the cavity and thus the cavity is lled from its inner portion toward the tooth surface, and all air is forced out by the filling material 135. While maintaining the air pressure on the dispenser, the barrel is removed from the cavity and the opening is preferably reclosed to provide a substantially smooth outer surface of the filling material. After proper curing time, the matrix maybe removed. When the matrix is in the form of the em-bodiment illustrated in FIGS. 4 and 5, the opening is advantageously reclosed by the repositioning of flap 34. When the matrix is in the form illustrated in FIGS. 6 and 7, the barrel 94 is inserted through opening 45 and into engagement with second strip 46. Further movement of :barrel 94 pierces strip 46 and allows the barrel to be disposed inside the cavity. Second strip 46 is advantageously resilient so that, when the barrel is withdrawn, the opening made by the barrel is substantially reclosed.

An ordinary matrix strip (not shown) may also -be utilized in this method. Such a strip may be secured in position as described above and a reclosable opening formed in the strip to allow the barrel to be inserted in the cavity. For this purpose, an advantageous dental tool, generally designated 142, is provided (FIGS. 15 and 16). The tool includes an elongate body portion 143 having a handle 144 adjacent one end and a barbed point 145 at its other end. The barbed point is advantageously of a pyramidal shape providing sharp points 145 at its base. The base is mounted on body 143 by means of a reduced body section 143' which is preferably of smaller size than the ibase to form points 145. The point 145' may be placed against the normal matrix to cut a slit therein and thereafter the pyramidal head inserted through the slit. The point 145 is then moved crosswise of the slit and retracted from the cavity thereby providing an opening into the cavity. This opening will have an irregular Hap at the exterior surface of the matrix. In this manner, there is no irregularity on the interior surface and the flap can be reclosed after filling of the cavity.

It is now deemed obvious that the method of the present invention may be utilized for filling cavities in the side of a tooth and that it may also be utilized `for repairing incisal edges of teeth or for capping a tooth, if desired. The method of the present invention provides a means for properly positioning a tooth form prior to dispensing of the filling material into the form. In this manner, no impression need be taken and the capping or tooth repair can be quickly performed during one office call. A capping or crowning performed with this method will thus cost from 1/3 to 1/s the cost of a repair which requires an impression and a number of ofi'ice calls.

While I have thus described a preferred method of the present invention and preferred apparatus for use in the method, the invention in its broader aspects is not limited to the specific steps and mechanisms shown and described, but departures may be made therefrom within the scope of the accompanying claims without departing from the principles of the invention and without sacrificing its chief advantages.

I claim:

1. A method of filling a cavity in a tooth comprising the steps of:

(a) preparing the cavity to be filled;

(b) securing a form in position over the cavity and contiguous to the tooth, and providing an opening in the form to communicate the cavity with the exterior of the form,

(c) inserting an end of a generally tubular barrel having an outer dimension less than the size of the cavity through the opening in the form and into the cavity so that the end of the tubular barrel is disposed inwardly of the form,

(d) introducing a iiowable filling material through the tubular barrel and into the cavity to fill the cavity from its inner portion toward the form; and

(e) removing the tubular barrel from the cavity.

2. A method as set forth in claim l wherein the step of securing a form in position includes doubling an elongate fiexible strip upon itself to provide a loop extending around the tooth with a central portion overlying the cavity and end portions in juxtaposition, pulling on the end portions to tighten the central portion against the tooth, and clamping the end portions in an area adjacent the tooth to hold the central portion tightly against the tooth.

3. A method as set forth in claim 1 wherein the form has a shape generally conforming to at least a portion of the outer surface of the tooth including at least a portion of the incisal edge thereof and has an open end whereby the form may be slipped onto the tooth; and the step of securing a form in position includes positioning the form with a portion overlying the cavity and aligning the occlusal surface thereof to provide a proper occlusion, wedging the form generally contiguous to the tooth with at least one wedge engaged with the form and an adjacent tooth, and applying a dental wax to the form and an adjacent surface to hold the form in position.

4. A method as set forth in claim 1 including the step of cutting a slot in the form with an instrument having a sharp point and a laterally extending barb, inserting the barb through the slot, moving the barb generally crosswise of the slot, and retracting the barb to thereby provide an opening in the form.

5. A method as set forth in claim 1 including: placing a quantity of flowable filling material in a container associated with the tubular barrel prior to inserting the tubular barrel through the opening in the form; and wherein the step of introducing the filling material through the tubular barrel comprises applying air pressure on a movable wall in the container to move the wall toward the tubular barrel and force the filling material into the cavity.

6. A method as set forth in claim 1 wherein the step of providing the opening in the forrn includes rupturing the form by the tubular barrel as the tubular barrel is inserted into the cavity.

7. A method of filling a cavity in a tooth comprising the steps of:

preparing the cavity to be filled;

providing a form including a first layer having a plurality of openings therein and a second layer of readily rupturable synthetic resins aiiixed to the first layer and spanning the openings;

securing the form over the cavity and contiguous to the tooth with at least one of the first layer openings positioned over the cavity; l

rupturing the second layer adjacent said .one of the first layer openings with a tubular barrel to provide an opening through the second layer;

inserting an end of the tubular barrel through the opening and into the cavity;

introducing a flowable filling material through the tubular barrel and into the cavity to fill the cavity from its inner portion toward the form; and removing the tubular barrel from the cavity.

8. A method of filling a cavity in a tooth compising the steps of:

preparing the cavity to be filled;

forming a generally U-shaped slot in a fiexible form to provide a fiexible flap movable laterally from the form in an area adjacent the ends of the slot to provide an opening in the form;

positioning the U-shaped slot over the cavity and securing the form contiguous to the tooth;

inserting an end of a generally tubular barrel having an outer dimension less than the size of the cavity through the opening in the form and into the cavity;

introducing a fiowable filling material through the tubular barrel and into the cavity to fill the cavity from the inner portion toward the form;

removing the tubular barrel from the cavity; and

thereafter closing the iiap to substantially cover the opening.

9. An apparatus for filling a cavity in a tooth comprising, in combination:

(a) a dental form contiguous to the surface of the tooth adjacent the cavity and including a wall overlying the cavity, said wall having an opening therein overlying the cavity, and means connected to the wall defining a closure for said opening;

(b) means engaged with the dental form for holding the same in position contiguous to the tooth; and

(c) means for dispensing a dental filling material in lastic state and including a cartridge for holding the filling material, a tubular barrel having an end sized for insertion through the dental form opening and into the cavity, and means for feeding the filling material from the cartridge into the cavity through the tubular barrel.

10. A combination as set forth in claim 9 wherein the dental form wall is in the shape of an elongated fieXible strip having a length greater than the circumference of the tooth for wrapping around the tooth; and including clamping means for grip-ping the strip and securing the same contiguous to the tooth, and means for engaging the strip and cutting the opening therein.

11. An apparatus for filling a cavity in a tooth comprising, in combination:

a dental form contiguous to the surface of the tooth adjacent the cavity and including a wall overlying the cavity, said wall comprising a first elongate strip having first and second ends, said first strip having a length greater than the circumference of the tooth and so arranged that a central portion intermediate the ends may be wrapped around the tooth, said first strip having a plurality of openings in said intermediate portion at least one of which overlies the cavity, a second strip of underlying the first strip and providing a closure for said openings, and the second strip being of readily rupturable material for rupturing `by a tool inserted through a selected one of the openings to communicate the cavity with the eXtension of the form;

means engaged with the dental form for holding the same in position contiguous to the tooth; and

means for dispensing a dental filling material in a plastic state and including a container for holding the filling material, a tubular barrel communicating with said container and having an end sized for insertion through the dental form opening and into the cavity, and means for feeding the filling material from the container through the tubular barrel and into the cavity to fill the cavity from its inner portion toward the dental form while the same is. in position overlying the cavity.

12. An apparatus for filling a cavity in a tooth as set forth in claim 11 wherein the end of the tubular barrel is shaped for rupturing the second strip for the dental form as the end is inserted through said one of the dental form openings.

13. A dental form for use in filling a cavity in a tooth and for lying contiguous to the tooth adjacent the cavity, said dental form comprising: a wall overlying the cavity and having at least one opening therein overlying the cavity, and means connected to the wall defining a closure for said opening.

14. A dental form as set forth in claim 13 wherein said opening is in the shape of a generally U-shaped slot, and said last-mentioned means is a exible iiap formed by said U-shaped slot, said fiap movable laterally from the wall generally about a line connecting the ends of the slot to provide access through said wall.

15. A dental form as set forth in claim 13 wherein the wall comprises a rst elongate strip having first and second ends vand a length greater than the circumference of the tooth, the first strip having an intermediate portion intermediate the ends for wrapping around the tooth and a plurality of openings in the intermediate portion; and wherein the last-mentioned means comprises a second flexible strip secured to the first strip and underlying the openings to provide a closure therefor, and the second strip being of readily rupturable material for rupturing by a tool inserted through a selected one of the openings in the rst strip.

16. A dental form as set forth in claim 13 wherein said wall comprises a first elongate strip having first and second ends, said first strip having a length greater than the circumference of the tooth and so arranged that a central portion intermediate the ends may be wrapped around the tooth, said first strip having a plurality of openings in said intermediate portion; and wherein said last-mentioned means comprises a second flexible strip secured to the first strip and underlying said openings to provide a. closure therefor, said second strip of readily rupturable material for rupturing by a tool inserted through la selected one of said openings overlying the cavity and into the cavity, and the second strip being sufficiently resilient to substantially cover the opening when the tool is removed.

.17. A dental form as set forth in claim 16 wherein the first strip is of colored material and the second strip is of substantially transparent material whereby the Openings in the first strip are well defined.

References Cited UNITED STATES PATENTS 2,648,906 8/1953 Holmes 32--60 3,082,531 3/1963 Jacobson 32--63 3,088,207 5/1963 Borsuk 32-60 3,147,552 9/1964 Goldman 32--63 OTHER REFERENCES Terry: Gingival Amalgam Repair, in Dental Digest, p. 79, item 6, February 1955.

LOUIS G. MANCENE, Primary Examiner.

R. PESHOCK, Assistant Examiner.

U.S. C1. X.R. 

